Device and method for endovascular treatment for causing closure of a blood vessel

ABSTRACT

An endovascular treatment method for causing closure of a blood vessel is provided. The method includes inserting into a blood vessel an optical fiber having a core through which a laser light travels and a spacer sleeve arranged around a distal portion of the core. A distal end of the core defines an enlarged light emitting face, which advantageously provides substantially lower power density while providing the same amount of total energy during a treatment session. After the insertion, laser light is applied through the light emitting face while the inserted optical fiber and spacer sleeve are longitudinally moved. The spacer sleeve positions the light emitting face away from an inner wall of the blood vessel and application of the laser light causes closure of the blood vessel.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional application of U.S. application Ser. No.12/100,309, filed Apr. 9, 2008, which claims priority under 35 U.S.C.Section 119(e) to U.S. Provisional Application Ser. No. 60/910,743,filed Apr. 9, 2007, U.S. Provisional Application Ser. No. 60/913,767,filed Apr. 24, 2007, and U.S. Provisional Application Ser. No.60/969,345, filed Aug. 31, 2007, all of which are incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to a medical device and method fortreating blood vessels, and more particularly to a laser treatmentdevice and method for causing closure of varicose veins.

BACKGROUND OF THE INVENTION

Veins are thin-walled and contain one-way valves that control bloodflow. Normally, the valves open to allow blood to flow into the deeperveins and close to prevent back-flow into the superficial veins. Whenvalves are malfunctioning or only partially functioning, however, theyno longer prevent the back-flow of blood into the superficial veins. Asa result, venous pressure builds at the site of the faulty valves.Because the veins are thin walled and not able to withstand theincreased pressure, they become what are known as varicose veins whichare veins that are dilated, tortuous or engorged.

In particular, varicose veins of the lower extremities is one of themost common medical conditions of the adult population. It is estimatedthat varicose veins affect approximately 25% of adult females and 10% ofmales. Symptoms include discomfort, aching of the legs, itching,cosmetic deformities, and swelling. If left untreated, varicose veinsmay cause medical complications such as bleeding, phlebitis,ulcerations, thrombi and lipderatosclerosis.

Endovascular thermal therapy is a relatively new treatment technique forvenous reflux diseases such as varicose veins. With this technique, thethermal energy is delivered by a flexible optical fiber orradiofrequency electrode that is percutaneously inserted into thediseased vein prior to energy delivery. For laser delivery, a treatmentsheath is typically inserted into the vein at a distal location andadvanced to within a few centimeters of the source of reflux. Once thetreatment sheath is properly positioned, a flexible optical fiber isinserted into the lumen of the treatment sheath and advanced until thefiber tip is near the treatment sheath tip but still protected withinthe sheath lumen.

Prior to laser activation, the treatment sheath is withdrawnapproximately 1-4 centimeters to expose the distal tip of the opticalfiber. After the fiber tip has been exposed a selected distance beyondthe treatment sheath tip, a laser generator is activated causing laserenergy to be emitted from the bare flat tip of the fiber into thevessel. The emitted energy heats the blood causing hot bubbles of gas tobe created. The gas bubbles transfer thermal energy to the vein wall,causing cell necrosis, thrombosis and eventual vein collapse. With thelaser generator turned on, both the optical fiber and treatment sheathare slowly withdrawn as a single unit until the entire diseased segmentof the vessel has been treated.

A typical laser system uses a 600-micron optical fiber covered with apolymer jacket and cladding layer. The fiber core extends through thefiber terminating in an energy emitting face.

With some prior art treatment methods, contact between theenergy-emitting face of the fiber optic tip and the inner wall of thevaricose vein is recommended to ensure complete collapse of the diseasedvessel. For example, U.S. Pat. No. 6,398,777, issued to Navarro et al,teaches either the means of applying pressure over the laser tip oremptying the vessel of blood to ensure that there is contact between thevessel wall and the fiber tip. One problem with direct contact betweenthe laser fiber tip and the inner wall of the vessel is that it canresult in vessel perforation and extravasation of blood into theperivascular tissue. This problem is documented in numerous scientificarticles including “Endovenous Treatment of the Greater Saphenous Veinwith a 940-nm Diode Laser: Thrombotic Occlusion After EndoluminalThermal Damage By Laser-Generated Steam Bubble” by T. M. Proebstle, MD,in Journal of Vascular Surgery, Vol. 35, pp. 729-736 (April, 2002), and“Thermal Damage of the Inner Vein Wall During Endovenous LaserTreatment: Key Role of Energy Absorption by Intravascular Blood” by T.M. Proebstle, MD, in Dermatol Surg, Vol. 28, pp. 596-600 (2002), both ofwhich are incorporated herein by reference. When the fiber contacts thevessel wall during treatment, intense direct laser energy is deliveredto the vessel wall rather than indirect thermal energy from the gasbubbles from heating of the blood. Laser energy in direct contact withthe vessel wall causes the vein to perforate at the contact point andsurrounding area. Blood escapes through these perforations into theperivascular tissue, resulting in post-treatment bruising and associateddiscomfort.

Another problem created by the prior art methods involving contactbetween the fiber tip and vessel wall is that inadequate energy isdelivered to the non-contact segments of the diseased vein. Inadequatelyheated vein tissue may not occlude, necrose or collapse, resulting inincomplete treatment. With the fiber tip in contact with the vessel wallrather than the bloodstream, hot gas bubbles are not created. The bubbleis the mechanism by which the 360 degree circumference of the vesselwall is damaged. Without the bubbles, it is possible for some veintissue to be under heated or not heated at all, resulting in incompletetreatment and possible recanalization of the vessel.

A related problem with endovascular laser treatment of varicose veinsusing a conventional fiber device is fiber tip damage during laserenergy emission caused by localized heat build up at the working end ofthe fiber, which may lead to thermal runaway. Thermal runaway occurswhen temperature at the fiber tip reaches a threshold where the coreand/or cladding begin to absorb the laser radiation. As the fiber beginsto absorb the laser energy it heats more rapidly, quickly spiraling tothe point at which the emitting face begins to burn back like a fuse.One cause of the heat build up is the high power density at the emittingface of the fiber. A conventional fiber includes a cladding layerimmediately surrounding the fiber core. Laser energy emitted from thedistal end of the device may create thermal spikes with temperaturessufficiently high to cause the cladding layer to burn back. Once thecladding layer is no longer present, laser energy will travel throughthe side wall of the fiber, causing additional energy loss and localizedheating. The fiber weakens under the high temperatures and may break.

In a related problem with conventional endovenous laser treatmentmethods, numerous procedural steps and accessory components are requiredto correctly position the optical fiber at the treatment site prior tothe application of laser energy. The procedure is time-consuming andexpensive partially due to the costs of the accessory components, whichincludes a treatment sheath designed to provide a pathway for the fiberto be advanced through the vessel to the source of reflux. Theintroduction of multiple components including the treatment sheathrequires a large access site puncture which may result in patientcomplications including bruising, prolonged bleeding, scarring, andinfection.

Therefore, it would be desirable to provide an endovascular treatmentdevice and method that protects the emitting face of the optical fiberfrom direct contact with the inner wall of vessel during the emission oflaser energy to ensure consistent thermal heating across the entirevessel circumference thus avoiding vessel perforation and/or incompletevessel collapse.

It is also desirable to provide an endovascular treatment device andmethod which decreases peak temperatures at the working end of the fiberduring the emission of laser energy thus avoiding the possibility offiber damage and/or breakage due to heat stress caused by thermalrunaway.

It is yet another purpose to provide an endovascular treatment deviceand method which reduces the number of accessory components andprocedural steps required to successfully treat a blood vessel.

Various other purposes and embodiments of the present invention willbecome apparent to those skilled in the art as more detailed descriptionis set forth below. Without limiting the scope of the invention, a briefsummary of some of the claimed embodiments of the invention is set forthbelow. Additional details of the summarized embodiments of the inventionand/or additional embodiments of the invention may be found in theDetailed Description of the Invention.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, an endovascular lasertreatment device for causing closure of a blood vessel is provided. Thetreatment device uses an optical fiber having a core through which alaser light travels and is adapted to be inserted into a blood vessel.An inner sleeve is arranged around a distal portion of the core suchthat both distal ends of the inner sleeve and the optical fiber coreform an enlarged light emitting face. An outer sleeve is arranged aroundthe inner sleeve. The outer sleeve acts as a spacer to position thelight emitting face away from an inner wall of the blood vessel.

As can be appreciated, the enlarged light emitting face providessubstantially lower power density while providing the same amount oftotal energy during a treatment session. The reduced power densityreduces peak temperatures near the emitting face and prevents thermalrunaway and device damage. The reduced average power density from theenlarged emitting face and the spacing of the emitting face away fromthe vessel wall due to the outer sleeve both serve to reduce thepossibility of vessel perforations, leading to less bruising,post-operative pain and other clinical complications.

In another aspect of the invention, an endovascular treatment method forcausing closure of a blood vessel is provided. The method involvesinserting into a blood vessel an optical fiber having a core and aspacer sleeve arranged around a distal portion of the core. The distalend of the fiber core defines a light emitting face. Once the opticalfiber is inserted, a laser light is applied through the light emittingface while the inserted optical fiber and spacer sleeve are movedlongitudinally to treat a defined segment of the blood vessel. Theapplication of laser light causes closure of the blood vessel.Advantageously, the spacer sleeve positions the light emitting face awayfrom an inner wall of the blood vessel, thereby reducing the possibilityof vessel wall perforations and less bruising.

In yet another aspect of the present invention, the spacer comprises aninner sleeve and an outer sleeve both arranged around a distal portionof the core to prevent the laser light from traveling laterally and toposition the light emitting face away from an inner wall of the vessel.The inner sleeve can be a heat resistive material such as ceramic andthe outer sleeve can be, for example, a metallic sleeve to providestructural integrity and strength to the distal section of the treatmentdevice. The outer sleeve can be especially important when the innersleeve is a ceramic material. Because the ceramic material is brittle,portions of the material can come apart due to heat stress and the outersleeve surrounding the inner sleeve can help dissipate heat and preventloose ceramic parts from traveling into the blood vessel, which can bevery dangerous.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing purposes and features, as well as other purposes andfeatures, will become apparent with reference to the description andaccompanying figures below, which are included to provide anunderstanding of the invention and constitute a part of thespecification, in which like numerals represent like elements, and inwhich:

FIG. 1A is a longitudinal plan view of the distal section of the opticalfiber with spacer assembly.

FIG. 1B is a partial cross-sectional view of the distal section of theoptical fiber with spacer assembly.

FIG. 2 depicts longitudinal plan views of the components of the distalsection of the fiber with spacer assembly prior to assembly includingthe optical fiber, the inner glass sleeve and the outer protectivesleeve.

FIG. 3A is a partial plan view of the distal section of the fiber andinner glass sleeve subassembly prior to fusing.

FIG. 3B is a partial plan view of the distal section of the fiber withinner glass sleeve subassembly after fusing of the distal end.

FIG. 4 is a partial plan view of the distal section of the fiber, innerglass sleeve assembled with the outer protective sleeve.

FIG. 5A illustrates a detailed longitudinal cross-sectional view of thedistal section of the optical fiber with spacer assembly.

FIG. 5B through 5E are cross-sections of FIG. 5A taken along lines A-A,B-B, C-C and D-D.

FIG. 6A is a partial plan view of the distal section of a conventionalprior art fiber illustrating the maximum propagation angle θ of thelaser beam given an emitting face diameter of E₁.

FIG. 6B is a partial plan view of the distal section of the opticalfiber/inner glass sleeve subassembly illustrating the relationshipbetween weld length L₁ and an increase in surface area of the emittingface E₂.

FIG. 6C is a partial plan view of the distal section of the opticalfiber/inner glass sleeve assembly illustrating the relationship betweenweld length L₂ and an increase in surface area of the emitting face E₃.

FIG. 7 is a partial plan view of the distal section of the optical fiberwith spacer assembly illustrating the maximum propagation angle exitingfrom the outer protective sleeve lumen.

FIG. 8A is a partial longitudinal cross-sectional view of the distalsegment of an alternative embodiment of an optical fiber with spacerassembly.

FIG. 8B is an end view of the embodiment of FIG. 8A shown from thedistal end of the device.

FIG. 9A is a partial plan view of a one embodiment of the fiber shaftillustrated with the distal section of the outer protective sleeve.

FIG. 9B is partial plan view of another embodiment of the fiber shaftillustrated with the distal section of the outer protective sleeve.

FIG. 10A through 10D illustrate various embodiments of the outerprotective sleeve.

FIG. 11A depicts a partial plan view of the distal section of the fiberwith a plan view of an alternative embodiment of the inner glass sleeve.

FIG. 11B illustrates the subassembly of the fiber and inner glass sleeveof FIG. 11A.

FIG. 12 is a partial plan view of the distal section of the opticalfiber with spacer assembly depicting an alternative embodiment of theouter protective sleeve.

FIG. 13 is a flowchart depicting the method steps for performingendovenous laser treatment using the device of FIG. 5.

FIG. 14 is a flowchart depicting the method steps for performingendovenous laser treatment using the device of FIG. 8A.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description should be read with reference to thedrawings, in which like elements in different drawings are identicallynumbered. The drawings, which are not necessarily to scale, depictselected preferred embodiments and are not intended to limit the scopeof the claims. The detailed description illustrates by way of example,not by way of limitation, the principles of the invention. In variousembodiments, and referring to FIGS. 1-14, presented herein are exemplarydevices and methods for endovenous laser treatment. FIGS. 1A and 1Billustrate the distal section of one embodiment of the optical fiberwith spacer assembly 1 from a partial plan view and partialcross-sectional view, respectively. Optical fiber with spacer assembly 1is comprised of an optical fiber 3, an insulative inner sleeve 13 and anoptional outer protective sleeve 19 coaxially surrounding the innerinsulative sleeve 13 and the distal portion of the optical fiber 3. Thespacer assembly includes the inner sleeve 13 and outer sleeve 19. Theoptical fiber 3 is comprised of a core 5, cladding layer 10 and aprotective fiber jacket 9 surrounding the cladding layer 10. Asdisclosed herein, the fiber core may range from 200-1000 microns indiameter. In one exemplary aspect, the core 5 is 600 microns.

The protective jacket 9, which can be susceptible to burn-back duringoperation, may be stripped back from the emitting face 11 of the fiber 3for a length of approximately 9 mm to where the proximal edge 17 ofinsulative inner sleeve 13 abuts up against protective jacket 9 of thefiber 3. Outer protective sleeve 19 extends from its distal most edge 21proximally over the fiber core 5 and a portion of the cladding andjacketed section of the fiber 3, terminating in proximal end 23.

In the embodiment shown in FIGS. 1A and 1B, the front emitting face 11of optical fiber 3 is recessed from the distal end 15 of insulativeinner sleeve 13 and further recessed from the distal end 21 ofprotective spacer sleeve 19. This configuration, with its heatinsulating properties helps to reduce temperatures at the distal end ofthe device, in turn preventing thermal runaway and possible melting ofthe core. In addition, the multi-layer design acts as a spacer toprevent contact between the front emitting face 11 of the fiber 3 andthe vessel wall, as will be explained in more detail below.

In one exemplary aspect, the axial distance between the energy emittingface 11 of the optical fiber 3 and the distal end 15 of the insulativeinner glass sleeve after assembly is approximately 0.006 inches. Thisdistance may range from flush with the emitting face 11 to approximately0.024 inches and may be in one aspect from about 0.003 inches to about0.024 inches. Generally, the distance is equal to approximately half thecross-sectional diameter of the fiber core 5. The insulative innersleeve 13 functions as a spacer by preventing any laser energy frombeing emitted from the side wall of the fiber core 5. Inner insulativesleeve 13 minimizes heat transmission at the distal end of the device,as will be described in more detail below. In the embodiment depicted inFIGS. 1A and 1B, the inner insulative sleeve 13 may be ceramic or othertype of high-temperature resistant materials such as, but not limited tocarbon or silica while the outer sleeve 19 may be a metallic sleeve suchas a stainless steel sleeve to provide structural integrity to thespacer assembly and enhanced ultrasound visibility.

In one exemplary aspect, the axial distance between the distal end ofthe energy emitting face 11 and distal end 21 of the outer protectivesleeve 19 after assembly is approximately 0.024 inches. This distancecan range from about 0 to about 0.030 inches, and in one aspect, fromabout 0.005 inches to 0.024 inches. Generally, the distance between theemitting face 11 and the distal end 21 of the outer protective sleeve 19should be selected such that the light emitted from the fiber emittingface 11 does not contact the inner wall of the outer protective sleeve19 as it is transmitted from the energy emitting face 11 of the fiber 3to the blood vessel lumen.

The distal end 21 of the outer protective sleeve 19 may extendapproximately 0.006 inches beyond the distal end 15 of the insulativesleeve 13 and approximately 0.012 inches beyond the distal end of theenergy emitting face 11. Alternatively, in another aspect, the distalend 21 of the outer protective sleeve 19 may be positioned flush withthe energy emitting face 11. In this aspect, the insulative inner glasssleeve 13 may extend distally beyond the energy emitting face 11 toshield the fiber core 5, thereby protecting the vessel wall frominadvertent contact with the fiber core 5 emitting face 11.

FIG. 2 depicts the distal section of the components of an alternativeembodiment of optical fiber with spacer assembly 1. The distal endsection includes optical fiber 3, an inner glass sleeve 13 and aprotective outer sleeve 19 prior to assembly. In one exemplary aspect,the fiber may be a 600 micron fiber, the core 5 may about 0.0239 inchesin diameter and coaxially surrounded by a thin cladding layer 10 with awall thickness of approximately 0.0003 inches. Where the cladding 10 ispresent, the outer diameter of the fiber 3 may be approximately 0.0246inches. With the addition of the protective jacket layer 9, the overallouter diameter of the fiber 3 is about 0.041 inches. The optical fiber 3is shown with the protective jacket 9 removed from the distal emittingface 11 to point 12. The cladding layer 10 is removed from the distalface 11 to point 30. The distance between the leading edge 12 of theprotective jacket layer 9 and the leading edge 30 of the cladding 10 maybe between approximately 0.25 mm and 2.00 mm in length. In one exemplaryaspect, the optical fiber 3 has a silica core and a polymer claddinglayer (e.g., fluoropolymer). In this aspect, both the jacket 9 andcladding layer 10 are stripped as shown in FIG. 2. In another aspect,the optical fiber may have a glass core 5 and a glass (e.g., dopedsilica) cladding layer 10. In this aspect, only the jacket 9 is strippedback, although the glass cladding layer 10 may also be stripped.

As illustrated in FIG. 2, the inner glass sleeve 13 may be comprised ofsilica (SiO2) or other glass or quartz material compositions with anindex of refraction equivalent or close to that of the fiber core 5.Having index-matching materials reduces the Fresnel reflection, whichminimizes emission of laser energy through the side surfaces of the coreby redirecting the laser beam in a forward direction, as is known in theart.

In one embodiment, the inner sleeve 13 may be approximately 0.236 inchesin length. A through lumen 25 extends from the distal edge 15 of theinner glass sleeve 13 to terminate at proximal edge 17. The outerdiameter of the inner glass sleeve 13 may be approximately 0.041 inchesin order to ensure that the outer surface of inner sleeve 13 is flushwith the outer surface of the unstripped portion of optical fiber 3after assembly, as shown in FIGS. 1A and 1B. The through lumen 25 isdimensioned so as to allow the stripped portion of the optical fiber 3to be inserted into and through the inner glass sleeve 13. For astandard 600 micron fiber, the lumen 25 of inner glass sleeve 13 may bedimensioned at about 0.0243 inches to accommodate a fiber core 5diameter of approximately 0.0239 inches. In the embodiment shown, theproximal edge 17 of inner glass sleeve 13 has an expanded luminaldiameter which tapers inwardly from a diameter of approximately 0.0280inches to the nominal through lumen diameter of about 0.0243 inches. Theinternally tapered wall 32 provides for ease of assembly when insertingthe fiber core 5 into the inner glass sleeve 13. It also allows forinsertion of the leading edge 30 of cladding 10 into the sleeve lumen 25to create an overlapping seal with the inner glass sleeve 13, as isshown more clearly in FIG. 3A.

In one aspect, as illustrated in FIG. 2, outer protective sleeve 19 isan optional element that may be included in the assembly. Outerprotective sleeve 19 is designed to space the energy emitting end 11 ofthe fiber away from the vessel wall to increase the durability of thedistal region of the optical fiber assembly 1, and to enhance trackingthrough the vessel during the insertion. In one aspect, sleeve 19 may becomprised of a heat conductive metal such as medical grade stainlesssteel, gold, platinum, or nitinol. These materials will dissipate heat.Alternatively, sleeve 19 may be comprised of heat-resistant materialssuch as ceramic, high-temperature polymer, carbon or silica.Heat-resistant materials minimize heat transmission to the surface ofthe sleeve. A combination of heat-conductive and heat-resistantmaterials may also be used to construct the distal end section of thefiber.

Inherently, a multilayer structure as disclosed herein will increase thevisibility of the distal end of device 1 under ultrasound or otherimaging modality. The sleeve 19 may be coated with a lubricous substanceto enhance trackability through the vessel. Outer protective sleeve 19may also be coated with a substance, such as titanium nitride (TiN) orgold, to reduce friction between the sleeve 19 and the vessel wall whenthe distal end of the device increases in temperature, as will bedescribed in more detail below.

In one aspect, outer protective sleeve 19 includes through lumen 27 thatextends from distal edge 21 to proximal edge 23. The diameter of lumen27 may be is approximately 0.042 inches so as to allow a snug fit whenassembled coaxially over the inner glass sleeve 13, which in oneexemplary aspect, may have an outer diameter of approximately 0.041inches. The outer protective sleeve 19 may be approximately 1.6 cm inlength, and when assembled with the fiber 3 and inner glass sleeve 13,extends proximally past the bare fiber section to coaxially surround thedistal section of the outer protective jacket 9. The distal end 21 ofouter protective sleeve 19 may be radiused or have an expanded diameterto enhance trackability, as will be discussed in more detail below.

FIGS. 3A, 3B and FIG. 4 illustrate the assembly steps for the opticalfiber with spacer assembly 1. As depicted in FIG. 3A, the first step inthe assembly process is to assemble the fiber 3 to the inner glasssleeve 13. Leading edge 17 of inner sleeve 13 is first slid over theenergy emitting face 11 of the optical fiber 3 and advanced until theinternal taper 32 of inner sleeve 13 contacts the leading edge 30 of thecladding 10. Inner sleeve 13 is advanced over the fiber core 5 until theleading edge 30 of cladding 10 is positioned within the lumen 25 atinternal sleeve taper 32. Once the inner diameter of the taper 32reaches about 0.0248 inches, the fiber 3 with cladding 10 is preventedfrom further advancement due to an interference fit, resulting in asmall overlap between the cladding 10 and inner glass sleeve 13. Theinterference fit and overlap between these two components helps tomaintain the position of the inner glass sleeve 13 on the fiber 3 duringthe next assembly step and also to seal off the proximal opening oflumen 25 of inner sleeve 13.

In one aspect of the assembly 1, as shown in FIG. 3A, an annularconstant-width air gap 31 is created between the inner glass sleeve 13and the fiber core 5. The air gap 31 may be about 0.0002 inches wide fora 600 micron fiber assembly, based on a core 5 diameter of 0.0239 inchesand an inner sleeve 13 diameter of 0.0243 inches. At this stage of theassembly process, air gap 31 extends longitudinally from the leadingedge 15 of inner sleeve 13 to the front face 30 of the cladding 10. Theinterference fit between the leading edge 30 of cladded fiber 10 and thetapered section 32 of inner glass sleeve 13 creates a seal, effectivelyclosing off the proximal opening of air gap 31. In one aspect, the frontemitting face 11 of the fiber core 5 may extend distally from theleading edge 15 of the inner glass sleeve 13. In one embodiment of a 600micron fiber, the fiber core 5 may extend approximately 1.5 mm distallyof the inner glass sleeve 13.

Once the inner glass sleeve 13 is properly aligned over the fiber 3, thedistal end 15 of inner sleeve 13 is welded or fused together with theenergy-emitting face 11 of the bare fiber core 5 to form distal endsection 29, as shown in FIG. 3B. In one aspect, both the fiber core 5and the inner glass sleeve are composed of equivalent silica material.In one aspect, a CO2 laser may be used to heat the two silica componentstogether to form a single fused end section 29 with an energy emittingface 11A. When the silica or other material of the inner glass sleeve 13is heated by the laser, it melts together with the fiber core 5material, forming a curved (convex as shown) semi-spherical distal endprofile, as shown in FIG. 3B. Other distal end profiles may optionallybe formed by modifying the fusing process or by post-fusing shaping,using techniques known in the art. Shapes may include but are notlimited to generally flat faced, with or without a radiused edge, convexand concave.

In one aspect, the fused end tip section 29 also effectively blocks thedistal end of the air gap 31, creating an enclosed air cavity. Thisenclosed air cavity 31 acts as a cladding by containing light withincore 5 and directing light energy in a forward manner. The cladding of aconventional fiber normally extends distally to just proximal to orflush with the energy emitting fiber core face 11. The cladding preventsemitted laser energy from exiting the side wall of the fiber core as thelaser beam travels through the fiber, but the distal end section of thefiber where the energy is emitted, is often subject to localized heatingduring use. This heat build-up at the distal end section of aconventional fiber may reach temperatures high enough to melt orotherwise damage the fragile cladding layer. Once the cladding has beendamaged, laser energy will escape radially through the side wall of thefiber core 5, causing increased localized heating with peak temperaturesthat may be high enough to further damage the distal end of the fiber.

In one exemplary aspect, the air gap 31 of the fiber assembly disclosedherein helps to reduce localized heat build-up and prevent thermaldamage to the working end of the device 1. Since air has a lowerrefractive index than silica, air gap 31 functions as cladding toprevent laser energy from escaping the core. By removing the cladding 9,the possibility of burn back of the cladding is eliminated. The fusedend tip section 29 ensures that blood will not contact the bare sidewalls of the fiber core 5. With conventional fibers, when the claddingburns back, blood in contact with the side wall of the bare fiber maycarbonize and cause additional laser energy loss through the side wall.Continued energy loss through the side walls of the fiber causes thefiber to weaken and eventually break. The assembly 1 with air gap 31eliminates problems due to cladding burn back and ensures that anyerrant laser energy that does escape through the core 5 will bereflected back into the core 5 by the presence of air gap 31, due to theair index of refraction. Thus, the air gap 31 serves as a“thermal-proof” waveguide to maintain the laser light within the core 5as it travels through the unclad portion of the fiber 3 by ensuring thatthe energy travels in a forward direction and does not escape radiallythrough the core side wall. The energy beam exits from the fused distalend section 29 through emitting face 11A of the fiber in a forwarddirection only.

FIG. 4 is an enlarged partial longitudinal plan view of the distal endsection of the optical fiber with spacer assembly 1 after the optionalouter protective sleeve 19 has been assembled over the inner glasssleeve 13/fiber 3 subassembly of FIG. 3. Prior to assembling the sleeve19 with the inner glass sleeve 13/fiber 3 assembly, the proximal end 17of the inner glass sleeve 13 is sealed against the cladding 10. Sealant35 is applied to the gap between the leading edge 12 of the jacket 9 andthe proximal edge 17 of the inner glass sleeve 13. A curablesilicone-based liquid adhesive is applied to the annular gap using asmall mandrel or other known application process. In one aspect, theliquid sealant may have a refraction index equivalent to the cladding10. The sealant 35 applied to the gap is sufficient to completely sealthe edge 17 of the inner glass sleeve 13 against the leading edge 30 ofcladding 10 as well as to fill the space created by the inwardly taperedsurface 32. Sealant 35 fills any gaps, cracks or other damage that mayhave occurred to the cladding 10 during the manufacturing process. Theadhesive qualities of sealant 35 provide added strength to the device byincreasing the bond strength between the fiber and inner glass sleeve13. Thus, sealant 35 acts as a supplemental cladding by preventing anylaser energy from escaping through the cladding 10 in this area. In oneaspect, the amount of sealant 35 applied may create an outer diameterthat is less than or equal to that of the inner glass sleeve 13 andprotective jacket layer 9 of the fiber 3.

Outer protective sleeve 19 is then aligned over the inner glasssleeve/fiber subassembly so that the distal end 21 of sleeve 19 ispositioned a distance distal to the emitting face 11A of fused end tipsection 29. This distance may be equal to or greater than zero, such as0.003 inches-0.008 inches or greater. In one aspect the sleeve 19 ispositioned approximately 0.0065″ from the distal end of the fused endtip 29. Adhesive may be applied to ensure that the outer protectivesleeve 19 is retained in the desired position during assembly.Specifically, adhesive 39 may be applied to the annular space betweenfiber jacket 9 and the inner wall of outer protective sleeve 19.Adhesive 39 may also be applied to the proximal section of the annularspace between the inner glass sleeve 13 and the outer sleeve 19. Asshown in FIGS. 4 and 5, adhesive 39 extends from the distal edge of airgap 37 distally to adhesive termination point 40. A ring of adhesive 39may also be applied to the proximal end of the outer protective sleeve19. This ring not only provides enhanced fixation of the sleeve 19 tothe fiber 3, but also provides a tapered outer profile to prevent thevein from catching on sleeve 19 as the device is withdrawn from thevessel.

Optionally, the proximal section of the outer protective sleeve 19 maybe crimped at crimp area 33 to enhance the attachment strength betweenthe sleeve 19 and the jacketed fiber 3. In one embodiment, the crimpingprocess may force the wall of the outer protective sleeve 19 to bepressed into the adhesive layer 39, as shown by indentions 38 in FIG.5A.

FIG. 5A illustrates an enlarged longitudinal cross-sectional view of theassembled distal end segment of the optical fiber with spacer assembly 1disclosed herein. FIG. 5B-5E are axial cross-sections of the distalsection of FIG. 5A taken along lines A-A, B-B, C-C and D-D,respectively. Referring to FIG. 5B, fiber 3 with its fiber core 5,cladding 10 and outer jacket 9 is coaxially surrounded by adhesive layer39, which ensures a secure attachment to outer protective sleeve 19.Referring next to FIG. 5C, fiber core 5 and cladding 10 are coaxiallysurrounded by sealant 35. As with FIG. 5B, the outer protective sleeve19 coaxially surrounds the subassembly, but the adhesive ring 39 hasbeen replaced with air gap 37. Air gap 37 is optional and is based onthe thickness of sealant 35 applied to the cladding 10 as well as theamount the sealant will shrink after drying. FIG. 5D illustrates thebare fiber core 5, reflective air gap 31, inner glass sleeve 13, outerair gap 41, and outer protective sleeve 19. FIG. 5E depicts the fuseddistal end section 29, comprised of the bare fiber core 5 fused togetherwith the inner glass sleeve 13 as previously described and outer air gap41 coaxially surrounded by the outer protective sleeve 19.

When laser energy travels down the fiber core 5, as it passes throughSection A-A, the laser energy is directed in a forward direction by thecladding 10 and protective jacket 9. As the wave reaches Section B-B,the cladding 10 and sealant 35 ensure a continued forward travel of theenergy. The silicone sealant provides additional protection bypreventing laser energy from passing through any cracks or openings inthe cladding inadvertently created during the manufacturing process. Asthe laser energy passes through Section C-C, any errant laser energypassing through and out of the side wall of core 5 due to the absence ofcladding 10 will be reflected back into the core 5 by air gap 31 due toits lower index of refraction. Once the laser energy reaches SectionD-D, the laser beam will pass through the fused distal end section 29and be directed in a forward direction through energy emitting face 11A.

FIG. 6A through 6C illustrate the laser fiber 3 with energy emittingfaces having several different surface areas and demonstrating therelationship between an increased surface area of the emitting face ofthe fiber and the average power density reduction. FIG. 6A is a partialplan view of the distal section of a conventional 600 micron fiberhaving a core 5 of diameter D1 with cladding 10 extending to the distalenergy emitting face 11. Rays 71 depict the boundaries of the energyemission zone with a maximum propagation angle θ of energy emitted fromthe core 5. Angle θ is based on the numerical aperture of the fiber andthe specific materials (core and cladding) being used. In one exemplaryaspect, given a numerical aperture of 0.37, the propagation angle θ maybe 16 degrees in water or blood, resulting in laser energy beingdistributed and emitted across the entire face 11 of the fiber, definedby diameter E1. In FIG. 6A, D1 is equal to energy emitting face 11diameter E1. The average density of the laser energy at the emittingface 11 is based on the surface area of the face 11. For example, a 600micron fiber has a surface area of about 0.0028 cm2, as shown in Table 1below. At a power setting of 14 Watts, laser energy is emitted throughthe energy emitting face 11 at an average power density of 5 KWatts/cm2.

Table 1 below illustrates the reduction in power density at the distalend of the fiber as the effective diameter (E) of the energy emittingface 11A is increased. The fusion length (L) is listed in microns. Thediameter of the effective emitting face E is recorded in microns. Thesurface area of the emitting face 11A is recorded in cm2. Due to thearcuate surface profile of the fused distal end section 29, the surfacearea data in Table 1, which is calculated using the area of a circleacross a flat horizontal plane, represents the minimum surface area ofenergy emitting face 11A because it does not account for the additionalsurface area due to the convex profile of 11A. Average power density atthe energy emitting face 11A is recorded in KWatts/cm2 and is based onan average power delivery of 14 Watts, the level commonly used forendovenous laser procedures, divided by the surface area of the emittingface. The recorded percent reduction in power density is relative tothat of a conventional 600 micron fiber depicted in FIG. 6A, and iscalculated as 100−(average power density/5.0).

TABLE 1 Power Density Reduction Table For 600 Micron Fiber CoreEffective Diameter of energy Surface area Fusion emitting of emittingAverage Power Reduction in Length (L) face (E) face density averagepower (microns) (microns) (cm²) (KWatts/cm²) density 0 600 0.0028 5.0 0% 227 720 0.0041 3.4 31% 265 740 0.0043 3.3 33% 303 760 0.0045 3.1 38%341 780 0.0048 2.9 41% 416 820 0.0053 2.7 47% 492 860 0.0058 2.4 51% 530880 0.0016 2.3 54% 606 920 0.0056 2.1 58% 681 960 0.0072 1.9 61% 719 9800.0075 1.9 63% 795 1020 0.0082 1.7 65% 833 1040 0.0085 1.6 67% 908 10800.0092 1.5 69% 984 1120 0.0099 1.4 71% 1022 1140 0.0102 1.4 72% 10981180 0.0109 1.3 74% 1135 1200 0.0113 1.2 75% 1211 1240 0.0121 1.2 77%1249 1260 0.0125 1.1 77% 1325 1300 0.0133 1.1 79% 1400 1340 0.0141 1.080% 1476 1380 0.0150 0.9 81% 1514 1400 0.0154 0.9 82% 1590 1440 0.01630.9 83% 1627 1460 0.0167 0.8 83% 1703 1500 0.0177 0.8 84%

FIG. 6B is a plan view of the distal section of inner glass sleeve 13and fiber 3 subassembly after the inner sleeve 13 and fiber 3 have beenfused to form tip 29 using a laser fusion process. This figureillustrates the increase in the emitting face 11A surface area. In thisaspect, the fiber core 5 is 600 microns with a diameter D1, equal to theconventional fiber core diameter D1 described in FIG. 6A. The maximumpropagation angle θ emitted from the fused distal end 29 remains 16degrees due to the core's numerical aperture of 0.37. As describedabove, the laser process fuses the inner glass sleeve 13 and the fibercore 5 creating a fusion length L1 that extends from the fused fiber tipsection 29 of the fiber 3 to the distal end of the air gap cavity 31.The fusion length L1 increases the effective surface area of theemitting face 11A, as indicated by effective diameter E2 of the emittingface 11A, which is larger than the fiber emitting face 11 diameter of E1of FIG. 6A. As an example, with reference to Table 1 above, a fusionlength L1 of 341 microns will increase the effective diameter E2 of theemitting face 11A from 600 microns to 780 microns. The surface area willincrease from 0.0028 cm2 to 0.0048 cm2. The average power density isreduced due to the increased surface area of the face 11A from 5.0 to2.9 KWatts/cm2, representing a 40.5% reduction in power density ascompared to the conventional fiber of FIG. 6A.

FIG. 6C illustrates a further increased fusion length L2. The fiber core5 is 600 microns and has a diameter D1 equal to the core diameter ofFIG. 6A. The laser fusion process creates a fusion between the innerglass sleeve 13 and the fiber core 5 with a fusion length L2 extendingfrom the fused distal end section 29 to the distal end of the air gapcavity 31. As indicated by E3 of the emitting face 11A, the diameter ofthe energy emitting face 29 has increased relative to diameter E1 ofFIGS. 6A and E2 of FIG. 6B. This increase in diameter to E3 results inan increased surface area and reduced average power density at theemitting face 29. In one non-limiting example, with reference to Table1, a fuse length L2 of 833 microns will increase the effective diameterof the emitting face 11A from 600 microns to 1040 microns. The surfacearea will increase from 0.0028 cm2 to 0.0085 cm2. The average powerdensity is reduced relative to a standard 600 micron core fiber due tothe increased surface area of the face 11A from 5.0 to 1.6 KWatts/cm2,representing a 66.7% reduction in average power density as compared tothe conventional fiber illustrated in FIG. 6A.

Thus in one important aspect, by increasing the fuse length L betweenthe fiber core 5 and silica cannula 13, an increase surface area of thefused energy-emitting face 11A is realized. The increased surface areaof the fused emitting face 11A results in a substantial reduction inaverage power density at the emitting face 11A of the device withoutcompromising the total amount of energy delivered to the vessel. As anexample, by doubling the effective diameter of the energy emitting face11A from 600 microns to 1200 microns, a 75% reduction in average powerdensity can be realized.

Conventional fibers can often reach very high temperatures sometimesexceeding several thousand degrees at the energy-emitting face where theenergy density is the greatest. Fiber components such as the claddingmay easily burn back when exposed to these high temperatures, resultingin exposure of bare fiber core. Thermal runaway may even cause the fibercore itself to overheat and burn back. Forward transmission of theenergy is compromised as laser energy escapes radially from the barecore. The errant laser energy often causes thermal runaway with extremetemperatures causing further erosion of the cladding and distal endsegment of the fiber. With the configurations disclosed herein, thereduced average power density at the distal end of the fiber resultingfrom an increased surface area of the emitting face reduces peaktemperatures and reduces the possibility of thermal run-away and devicedamage, without a decrease in the total amount of energy deliveredduring the treatment session. The reduced average power density alsoreduces the possibility of vessel perforations caused by extremetemperatures, leading to less bruising, post-operative pain and otherclinical complications.

FIG. 7 is an enlarged partial plan view of the distal section of thedevice of the fiber with spacer assembly 1. The outer protective sleeve19 is assembled as previously described with adhesive 39 and crimp area33, ensuring attachment to the fiber 3/inner glass sleeve 13 assembly.Laser energy is emitted from the distal end of the fiber with a maximumpropagation angle θ of the energy emission zone is defined by boundaryrays 71. Laser energy passes through fused end section 29, is emittedout of emitting face 11A and into and through the lumen 27 of outerprotective sleeve 19 at maximum angle θ. As illustrated in FIG. 7, outerboundary rays 71 do not contact the inner wall or leading edge 21 ofouter protective sleeve 19.

The inner glass sleeve 13/fiber core 3 fusion length L3 determineslength L4, defined as the length between the distal most edge of thefused end section 29 and the leading edge 21 of the outer protectivesleeve 19. L4 represents the maximum extension of the outer protectivesleeve 19 that can be used such that the laser energy exiting theemitting face 11A at the maximum angle θ does not contact the inner wallof outer protective sleeve 19. By controlling the dimensions of L3 andL4, laser energy following the maximum wave propagation angle θ will bedirected into the blood vessel without directly hitting the distal endof the outer protective sleeve 19. Thus, overheating of the outerprotective sleeve 19 caused by direct laser beam contact can be reducedwith this invention, while still ensuring that the energy emitting face11A is prevented from inadvertent contact with the vein wall.

The outer protective sleeve 19 may have a light-reflective coating suchas gold. This coating may also be applied to a portion of the inner wallof the outer protective sleeve 19 along length L4. When a peripheralportion of the emission zone 71 beyond the emitting face 11A overlaps orotherwise contacts the distal portion of the inner wall of sleeve 19,the optional coating may increase reflection of laser energy into thevessel. Specifically any laser energy contacting the L4 portion of thesleeve 19 will be reflected off the sleeve and back into the treatmentregions by the reflective qualities of the coating thereby avoidingemission energy loss and/or minimizing thermal build-up at the distalend of the device.

Referring now to FIG. 8A and FIG. 8B, an alternative embodiment of thefiber with spacer device 201 is illustrated. FIG. 8A is a partiallongitudinal cross-sectional view of the distal segment of element 201.FIG. 8B shows an end view of the embodiment in FIG. 8A illustrated fromthe distal end of the device. The components in assembly 201 are of asmaller size and diameter compared to optical fiber with spacer assembly1 of FIG. 5 to allow for direct advancement through the treatment vesselwithout the use of a treatment sheath or other tracking accessory. Fiberwith spacer element 201 includes fiber 203, inner glass sleeve 213 andouter protective sleeve 219. As with previous embodiments, the fiber 203with protective jacket layer 209 and cladding 210 extends partiallythrough the outer protective sleeve 219. The protective jacket layer 209terminates at distal end 212, adjoining air gap 237. The cladding 210terminates just inside the inner glass sleeve 213 at the internal taper232. Inner glass sleeve 213 coaxially surrounds fiber core 205 betweenwhich a constant-width annular air gap 231 is formed. The fiber core 205further extends distally terminating at fused distal end section 229 inemitting face 11A. Coaxially positioned in surrounding relationship withthe fiber/inner glass sleeve subassembly is the outer protective sleeve219. Outer protective sleeve 219 extends distally beyond fused emittingface 11A terminating in leading edge 221.

In one example, the fiber core 205 is comprised of pure silica with anumerical aperture of 0.37 and may have a diameter of 500 microns orless, such as 400 microns. Corresponding outer diameter dimensions ofother elements include the cladding 210 at 430 microns and outer jacketlayer 209 at 620 microns, both of which extend distally into the outerprotective sleeve 219. Outer jacket 209 terminates at point 212 and thecladding 210 terminates within the inner glass sleeve 213 just distal ofthe inner glass sleeve tapered wall section 232. In one exemplaryaspect, inner glass sleeve 213 may have an outer diameter of 0.043inches. Inner glass sleeve 312 may have an internal through lumen ofapproximately 0.0165 inches in diameter tapering outwardly to a flareddiameter of 0.020 inches at proximal edge 232, an outer diameter of0.033 inches and a length of 0.238 inches. The outer protective sleeve219 has an internal through lumen 227 with a diameter of about 0.035inches. With these dimensions, the annular air gap 231 is approximately0.0001 inches in width, and as previously described, is closed at theproximal end by cladding 210 and silicone sealant ring 235 and by thefused inner glass sleeve/fiber tip 229 at the distal end.

The distal end view of the device, shown in FIG. 8B, illustrates thefused distal end section 229 with energy emitting face 11A coaxiallysurrounded by the outer protective sleeve 219. A small air gap 241exists between fused end section 229 and sleeve 219. Shown with hiddenlines is the air gap 231 which coaxially surrounds the fiber core 205and the outer boundary of the energy emitting face 11A. The expandeddistal end 226 of sleeve 219 is illustrated by apex 243.

Referring to FIGS. 8A, 8B and 10A, outer protective sleeve 219 iscomprised of a proximal edge 223, a cylindrical main body 224, anoutwardly bulging distal body/portion 226 extending from the main body,with a through lumen 227 of constant diameter of approximately 0.035inches extending from edge 223 to tip 221. As shown in FIG. 8A, thebulging distal body 226 has a bulb-like profile or shape. The main body224 may be approximately 0.360 inches in length. The outwardly bulgingbody 226 extends distally from the main body 224 for approximately 0.040inches. Outwardly bulging distal body 226 includes a radially outwardlytapering section 245, which in one aspect may have a taper angle of 170degrees relative to the longitudinal axis of fiber core 205. Taperingsection 245 extends outwardly to a maximum diameter at apex 243, whichin the instant embodiment may have an outer diameter of 0.054 inches.Thus, at the apex 243, the wall thickness of sleeve 19 may beapproximately 0.0095 inches, which is approximately twice the thicknessof the main body wall which is approximately 0.0055 inches. Theoutwardly bulging distal body 226 tapers radially inward from apex 243to distal end 221, which may be radiused to eliminate any sharp edgesand provide a smooth leading tip.

The increased wall thickness and surface area of the bulging distal body226 relative to the main body 224 provides enhanced trackability wheninserting and advancing the fiber 203 to the treatment location. Thedistal end segment 226 acts as an atraumatic leading tip, which will notperforate the vessel wall if contact is made between outer protectivesleeve 219 and the vessel wall during advancement through the vein. Theadditional surface area and material at the distal end of the devicealso provides enhanced trackability and pushability through the vessel.The additional material at the distal body 226 of sleeve 219 addsstructural strength to the distal end of the device making it lesssusceptible to thermal damage by reducing peak temperatures at thedistal end of the device.

In one aspect, use of a smaller fiber such as a 400 micron fiberprovides a sufficiently flexible fiber shaft to allow insertion andadvancement through the vein without having to use a guidewire ortreatment sheath. Due to the small diameter, the fiber with spacerassembly 201 may be inserted directly through a micro-access set intothe vein, thereby eliminating several procedural steps as will bedescribed in more detail below. A 400 micron fiber is also capable ofdelivering sufficient energy to cause vessel occlusion. It may bedesirable to use a fiber with a diameter of 430 microns to provideadditional fiber core diameter at the proximal end where the fiberconnects to a laser source. The larger diameter core will allow forslight misalignment of the fiber core to laser source withoutcompromising energy transmission or damaging the laser generator.

Although the fiber diameter is smaller than the previously disclosed 600micron fiber, the creation of a fused distal end section 229 with itsfusion length L will also effect the reduction in power density at theemitting face 11A. Table 2 below lists the average reduction in powerdensity based on increasing fusion lengths.

TABLE 2 Power Density Reduction Table For a 400 Micron Fiber CoreEffective Diameter of energy Surface area Fusion emitting of emittingAverage Power Reduction in Length (L) face (E) face density averagepower (microns) (microns) (cm²) (KWatts/cm²) density 0 400 0.0013 11.1 0% 200 502 0.0020 7.1 36% 300 553 0.0024 5.8 48% 400 604 0.0029 4.9 56%500 655 0.0034 4.2 63% 600 705 0.0039 3.6 68% 700 756 0.0045 3.1 72% 800807 0.0051 2.7 75% 900 858 0.0058 2.4 78%

FIG. 9A is a partial plan view of the fiber with spacer assemblyillustrating a fiber 3 and proximal section of the outer protectivesleeve 19. Fiber 3 is comprised of a core 5, a cladding layer 10,coaxially surrounded by protective jacket 9, and attached to outerprotective sleeve 19 as previously disclosed. As illustrated in FIG. 9A,the device may include visual markings/markers 18 on the outer jacket 9of fiber 3. Markings 18 are used by the physician to provide a visualindication of insertion depth, tip position and speed at which thedevice is withdrawn through the vessel during delivery of laser energy.The markings 18 may be numbered to provide the physician with anindication as to distance from the protective sleeve 19 and/or theemitting face 11A of the fiber to the access site during pullback. Themarkings 18 may be positioned around the entire circumference of thefiber shaft or may cover only a portion of the shaft circumference.

As the device is pulled back, the markings appear at the skin surfacethrough the access site and provide the physician with a visualindication of pullback speed. In one example, given a 10 watt powersetting, the rate at which the device is retracted is approximately 5-8seconds per cm. In one exemplary aspect, markings 18 may beapproximately 1 mm in width and be aligned at 1 cm increments.Optionally the distal most set of markings 59 may be uniquely configuredto visually alert the physician that the distal end of the fiber withthe outer protective sleeve 19 is near the access site, indicating thatthe procedure is complete.

FIG. 9B illustrates yet another embodiment of the fiber with spacerassembly 1. In this embodiment, a metallic reinforcement element 20coaxially surrounds fiber 3 and extends from the proximal end of thefiber (not shown) to the distal end section adjacent to or overlappingwith the optional outer protective sleeve 19. Metallic reinforcementelement 20 may be comprised of metallic strands 69 arranged in anoverlapping braided pattern, as shown in FIG. 9B, or other patterns suchas spiral or longitudinal or horizontally arranged strands. In oneexemplary aspect, strands 69 are embedded within a polymer layer 79.Layer 79 may be an extruded urethane, Teflon shrink tubing or otherplastic material known in the art. The outer surface of metallicreinforcement element 20 may be hydrophilically coated to reducefriction during advancement and retraction of the fiber. In one aspect,metallic strands 69 may optionally overlap with the proximal section ofouter protective sleeve 219. Overlapping metallic strands 40 may besandwiched between the inner wall of outer protective sleeve 219 and thefiber jacket 9. The polymer layer 79 may optionally be removed from themetallic strands 40 and the strands welded to the outer protectivesleeve 19.

Metallic reinforcement element 20 provides several advantageousfunctions. Visibility of the entire fiber shaft 3 under ultrasoundimaging is enhanced due to the echogenicity of the metallic strands 69.Enhanced visibility of the fiber shaft provides the physician with anultrasonically visible target when injecting tumescent fluid into theanatomical peri-venous sheath along the length of the vein prior to thedelivery of laser energy, as is described in more detail below. Enhancedvisibility of the fiber shaft provides the physician with a visualtarget for positioning the tumescent injection needle accurately betweenthe outer vein wall and the perivenous sheath without entering the veinlumen. If the needle tip inadvertently enters the vessel lumen and comesinto contact with the fiber, the presence of the metallic reinforcementelement 20 provides an added level of protection to the fiber shaft toprevent damage to the cladding 10 and core 5 from the sharp needle tip.Typically, tumescent fluid is injected all along the vessel beingtreated using a small gauge needle. The needle tip may inadvertentlycontact the fiber shaft during this step, causing damage. The additionalreinforcement layer prevents the needle from damaging the protectivejacket 9 and the cladding 9, thereby preventing the possibility of laserenergy escaping radially from the fiber core 5 through the compromisedjacket or cladding. In another aspect, the optional weld between theouter protective sleeve 19 and the bare metallic strands 40 increasesthe overall structural integrity of the distal end segment by providinga supplemental attachment region.

Other outer protective sleeve 19 configurations are illustrated in FIGS.10B through 10D. The sleeve 319 profile may include a bulging distal endsegment/portion 326 as shown in FIG. 10B. In this embodiment, distal endsegment 326 includes an outwardly tapering section (conical shapeportion) 334 which transitions to cylindrical segment 332, which has aconstant diameter, before terminating in radiused end 321. FIG. 10Cillustrates a plan view of outer protective sleeve 419 showing a bulgingdistal end segment/portion 426 that extends from main body 424 radiallyoutward at a constant angle (conical shape portion) before terminatingin radiused end tip 421. FIG. 10D illustrates yet another embodiment ofsleeve 519. The sleeve includes a cylindrical portion 524A and anoutwardly bulging portion 526A, 524B and 526B. Conical shape portion526A extends distally from the cylindrical portion 524A with increasingdiameter. Cylindrical portion 524B extends from conical shape portion526A and has a larger diameter than that of cylindrical portion 524A.Second conical shape portion 526B extends from cylindrical portion 524Band has a radiused end (distal tip) 521. A through lumen 527 extendsfrom distal tip 521 and includes an internal transition from a largerdiameter section 527A to a smaller diameter section 527B beforeterminating at proximal end 523. This embodiment may be used toaccommodate a larger inner diameter inner glass sleeve relative to thefiber outer diameter. The multiple tapered segments of FIG. 10D alsoprovide a more gradual taper transition across the entire longitudinallength of the outer protective sleeve 519, which allows for bothenhanced tracking of the device to the target treatment location andenhanced retracting of the device through the vein during laserdelivery.

FIGS. 11A and 11B depict the fiber assembly 601 in which the inner glasssleeve 613 is illustrated as an additional embodiment. The embodiment ofFIG. 11 is similar to that of FIGS. 2 and 3, except that the sleeve 613has a closed distal end 627 prior to being fused with the fiber core 5.Fiber 3 includes a core 5, cladding 10, and outer protective jacket 9with an energy emitting face 11. Cladding 10 has been partially strippedback to edge 30, and protective jacket 9 has also been partiallystripped back to edge 12, as previously described. As shown in FIG. 11A,inner glass sleeve 613 includes a proximal edge 617, and leading endwall 627 and a cavity 675 extending proximally from wall 627 to edge617. To assemble with the sleeve 613 with fiber 3, the front emittingface 11 of fiber 3 is inserted into and advanced through cavity 675until it abuts up against wall 627. A CO2 laser is then used to heat thetwo silica components 11 and 627 together to form a single fused end tip(not shown) with a radiused surface profile so that an enlarged emittingface is created. Similar to the embodiment as shown in FIGS. 2 and 3,the constant-width air gap 631 acts as a cladding layer to reduce lighttransmission loss. The fused tip reduces the thermal load (average powerdensity) at the distal tip 627 and prevents erosion of the tip section.

FIG. 12 is an enlarged partial plan view of the distal section of thedevice of the fiber with spacer assembly 1 with an outer protectivesleeve 19 whose distal end 21 terminates proximally of the energyemitting face 11A. The outer protective sleeve 19 may be aligned overthe inner glass sleeve 13 so that fused end section 29 of the deviceextends distally beyond the leading edge 21 of outer protective sleeve19. In one aspect, the leading edge 21 of outer protective sleeve 19 maybe between 0.5-5.0 mm proximal to emitting face 11A. The protectivespacer 19 may be of the same length as previously described or may beshorter in overall length. Other than the recessed alignment relative tothe emitting end 29, the outer protective sleeve 19 is assembled aspreviously described with adhesive 39 and crimp area 33. The outerboundaries of the energy emitting face 11A are defined by maximumpropagation angle θ of the energy emission zone 71. As indicated by rays71, the energy emitting face 11A is protected from contact with thevessel wall by the leading radiused surface 73 of inner sleeve 13. Theouter protective sleeve 19 in this embodiment ensures that laser energyemitting from emitting face 11A will not come into contact or reflectoff the distal section of the outer protective sleeve 19, regardless ofthe maximum propagation angle θ of the energy emission zone. Thus, theouter protective sleeve 19 provides increased structural integrity andstrength to the distal section of the device while minimizingoverheating of the outer protective sleeve 19 caused by peripheral laserbeam contact.

Methods of using the optical fiber with spacer assembly for endovenoustreatment of varicose veins and other vascular disorders will now bedescribed with reference to FIGS. 13 and 14. FIG. 14 illustrates theprocedural steps associated with performing endovenous treatment usingthe optical fiber with spacer assembly 1. To begin the procedure, thetarget vein is accessed using a standard Seldinger technique well knownin the art. Under ultrasonic guidance, a small gauge needle is used topuncture the skin and access the vein (100). A 0.018 inches guidewire isadvanced into the vein through the lumen of the needle. The needle isthen removed leaving the guidewire in place (102).

A micropuncture sheath/dilator assembly is then introduced into the veinover the guidewire (104). A micropuncture sheath dilator set, alsoreferred to as an introducer set, is a commonly used medical kit, foraccessing a vessel through a percutaneous puncture. The micropuncturesheath set includes a short sheath with internal dilator, typically 5-10cm in length. This length is sufficient to provide a pathway through theskin and overlying tissue into the vessel, but not long enough to reachdistal treatment sites. Once the vein has been access using themicropuncture sheath/dilator set, the dilator and 0.018 inches guidewireare removed (106), leaving only the micropuncture introducer sheath inplace within the vein (107). A 0.035 inches guidewire is then introducedthrough the introducer sheath into the vein. The guidewire is advancedthrough the vein until its tip is positioned near the sapheno-femoraljunction or other starting location within the vein (108).

After removing the micropuncture sheath (110), a treatmentsheath/dilator set is advanced over the 0.035 inches guidewire until itstip is positioned near the sapheno-femoral junction or other refluxpoint (112). Unlike the micropuncture introducer sheath, the treatmentsheath is of sufficient length to reach the location within the vesselwhere the laser treatment will begin, typically the sapheno-femoraljunction. Typical treatment sheath lengths are 45 and 65 cm. Once thetreatment sheath/dilator set is correctly positioned within the vessel,the dilator component and guidewire are removed from the treatmentsheath (114, 116).

The optical fiber with spacer assembly 1 is then inserted into thetreatment sheath lumen and advanced until the fiber assembly distal endis flush with the distal tip of the treatment sheath (118). A treatmentsheath/dilator set as described in co-pending U.S. patent applicationSer. No. 10/836,084, incorporated herein by reference, may be used tocorrectly position the protected fiber tip with spacer assembly 1 of thecurrent invention within the vessel. The treatment sheath is retracted aset distance to expose the fiber tip (120), typically 1 to 2 cm. If thefiber assembly has a connector lock as described in U.S. Pat. No.7,033,347, also incorporated herein by reference, the treatment sheathand fiber assembly are locked together to maintain the 1 to 2 cm fiberdistal end exposure during pullback.

The physician may optionally administer tumescent anesthesia along thelength of the vein (122). Tumescent fluid may be injected into theperi-venous anatomical sheath surrounding the vein and/or is injectedinto the tissue adjacent to the vein, in an amount sufficient to providethe desired anesthetic effect and to thermally insulate the treated veinfrom adjacent structures including nerves and skin. Once the vein hasbeen sufficiently anesthetized, laser energy is applied to the interiorof the diseased vein segment. A laser generator (not shown) is turned onand the laser light enters the optical fiber 3 from its proximal end.While the laser light is emitting laser light through the emitting face,the treatment sheath/fiber assembly is withdrawn through the vessel at apre-determined rate, typically 2-3 millimeters per second (124). Thelaser energy travels along the laser fiber shaft through theenergy-emitting face of the fiber and into the vein lumen, where thelaser energy is absorbed by the blood present in the vessel and, inturn, is converted to thermal energy to substantially uniformly heat thevein wall along a 360 degree circumference, thus damaging the vein walltissue, causing cell necrosis and ultimately causing collapse/occlusionof the vessel.

The optical fiber with spacer assembly 1 according to the invention hasseveral advantages over methods of use of conventional bare-tippedfibers. The energy emitting face of the fiber assembly is protected fromany inadvertent contact with the vessel wall during withdrawal of thedevice through the vessel during energy delivery. Numerous studies havedemonstrated that contact between the energy emitting face of the fiberand the vein wall causes vessel perforations resulting inpost-procedural bruising, pain and swelling. The inner glass sleeve andoptional outer protective sleeve function to space the energy emittingfiber distal tip away from the vessel wall and to protect the emittingface within the outer protective sleeve recess, thus eliminating anypossibility of contact between the fiber emitting face and the vesseland the resulting perforations, even when withdrawing through anextremely tortuous vessel.

The fiber with spacer assembly 1 of the current invention also isadvantageous in controlling the direction and density of laser energyemitted from the emitting face of the fiber. The inner glass sleeve withannular air gap cavity ensures that the laser energy is contained in thefiber core and emitted in a forward direction only. Errant laser energymay compromise the structural integrity of the fiber tip by causingtemperature spikes, localized heat build-up at the distal tip sectionand possible thermal run-away as described above. The inner glass sleeveand air gap cavity act to re-direct any errant laser energy back intothe fiber core thus preventing reflected laser energy from beingabsorbed by the outer protective sleeve or other distal end elements.

In yet another aspect of the method of this invention, reduction in theaverage power density on the energy-emitting face of the fiber lowersthe peak temperatures and thermal build-up at the distal end of thedevice while still delivering laser energy equivalent to a conventionalbare fiber. As the fiber assembly is withdrawn through the vessel,clinically beneficial levels of laser energy are delivered to the vesselwithout heating up the distal end of the fiber assembly, greatlyreducing the likelihood of thermal runaway. Thermal runaway createsextreme temperature variations that may result in incompletely treatedvessel segments, perforation in the vein wall, carbonization tracks, anddevice failure.

FIG. 13 is a flowchart illustrating the procedural steps of thepreferred method of endovenous treatment using the optical fiber withspacer assembly 201, which is depicted in FIGS. 8A and 8B. In thisprocedure, the use of a treatment sheath is not required due to theflexibility and trackability of the smaller diameter fiber device. Aswith the previously described method, the vein is accessed using a smallneedle and a 0.018 inch guidewire (100, 102). A micropuncture introducersheath/dilator is then introduced into the vein over the guidewire (105)to dilate the insertion site. The dilator and guidewire are then removed106, leaving the 4 F sheath in place. Because the treatment sheath iseliminated with this method, the insertion site does not requiredilation larger than the diameter of the 4 F micropuncture sheath. Thus,the size of the micropuncture sheath/dilator assembly may be relativelysmall and the resulting access site puncture may be reduced relative toconventional methods. As is well-known in the art, smaller access sitesare desirable as evidenced by the reduced occurrence of patientcomplications which may include hematoma, bleeding, pain, access sitescarring and infection.

The 0.018 inch guidewire and dilator/sheath are removed from thepatient, after which the optical fiber with spacer assembly is inserteddirectly into the vein through the 4 F micropuncture sheath (119)without the aid of a treatment sheath. The fiber assembly is advancedforward through the vessel using the outwardly bulging distal tip of theouter protective sleeve 19 to facilitate advancement and trackingthrough tortuous vessels. The expanded distal end of the outerprotective sleeve provides an atraumatic leading end, which will notcatch or snag on the vessel wall as the fiber assembly is beingadvanced, but instead will glide along the vein wall. Because the fiberassembly is smaller and more flexible than larger diameter conventionalfibers and can track easily through the vessel without a treatmentsheath, numerous conventional procedural steps may be eliminated. Forexample, the step of inserting, advancing and positioning the 0.035inches guidewire at the highest point of reflux within the vein iseliminated. The 0.035 inches guidewire is required in conventionalmethods in order to advance a treatment sheath/dilator set through thevessel. The steps of inserting a treatment sheath/dilator set, removingthe dilator and removing the 0.035 inches guidewire are eliminated.Instead, the fiber assembly according to the present invention isinserted and advanced in the vessel without these procedure components.In addition, the steps of retracting the treatment sheath to expose thedistal 1-2 cm of the fiber and locking the two components together priorto the delivery of laser energy is eliminated. In conventionalprocedures, misalignment of the fiber tip may result in thermal energybeing transferred to the treatment sheath tip, resulting in potentialdamage to the treatment sheath and/or patient complications. With theimproved and simplified method disclosed herein, the fiber assembly ispositioned relative to the sapheno-femoral junction or other refluxpoint without having to align the fiber tip with a treatment sheath tip.

Laser energy is applied to the interior of the diseased vein segment asthe fiber assembly is withdrawn, preferably at a rate of about 2-3millimeter per second (124). The process of controlling the pullbackspeed through the vessel in conventional methods is typically controlledby the use of graduated markings on the treatment sheath. Since thetreatment sheath is not present with the current method, the physician'spullback speed may be controlled either by markings positioned along thefiber shaft or by using an automated pullback mechanism, as is known inthe art. The procedure for treating the varicose vein is considered tobe complete when the desired length of the target vein has been exposedto laser energy.

The method of endovenous laser treatment disclosed herein has numerousadvantages over prior art treatment devices and methods. The design ofthe distal end segment of the fiber assembly with its inner glass sleeveand optional outer protective sleeve provide the benefits previouslydescribed. In addition to these previously described benefits, the fiberwith spacer assembly, with its smaller fiber size and atraumatic leadingdistal tip result in the elimination of multiple procedure stepsrequired in conventional methods. Accessory components such as the 0.035inch guidewire, treatment sheath and fiber/sheath locking connectionsare eliminated, thus reducing the overall cost of the device andprocedure. Since the procedure has been simplified, the time associatedwith the eliminated steps is saved resulting in a faster, safer and morecost-effective procedure. The leading atraumatic distal tip not onlyprovides a mechanism for easily tracking and advancing the fiberassembly in an atraumatic way through tortuous anatomy, but alsofacilitates the alignment of the fiber emitting face relative to thesource of reflux, due to the enhanced ultrasonic visibility of thedistal tip section.

The above disclosure is intended to be illustrative and not exhaustive.This description will suggest many variations and alternatives to one ofordinary skill in this art. All these alternatives and variations areintended to be included within the scope of the claims where the term“comprising” means “including, but not limited to”. Those familiar withthe art may recognize other equivalents to the specific embodimentsdescribed herein, which equivalents are also intended to be encompassedby the claims.

Further, the particular features presented in the dependent claims canbe combined with each other in other manners within the scope of theinvention such that the invention should be recognized as alsospecifically directed to other embodiments having any other possiblecombination of the features of the dependent claims. For instance, forpurposes of claim publication, any dependent claim which follows shouldbe taken as alternatively written in a multiple dependent form from allprior claims which possess all antecedents referenced in such dependentclaim if such multiple dependent format is an accepted format within thejurisdiction (e.g., each claim depending directly from claim 1 should bealternatively taken as depending from all previous claims). Injurisdictions where multiple dependent claim formats are restricted, thefollowing dependent claims should each be also taken as alternativelywritten in each singly dependent claim format which creates a dependencyfrom a prior antecedent-possessing claim other than the specific claimlisted in such dependent claim below.

This completes the description of the selected embodiments of theinvention. Those skilled in the art may recognize other equivalents tothe specific embodiments described herein which equivalents are intendedto be encompassed by the claims attached hereto.

What is claimed is:
 1. An endovascular treatment method for causingclosure of a varicose vein comprising: inserting into a varicose vein anoptical fiber having a core through which a laser light travels,wherein: the core has a proximal portion surrounded directly by a firstcladding layer and a distal portion disposed distally of the proximalportion and surrounded directly by a second cladding layer that isdifferent than the first cladding layer; a sleeve is arranged around thedistal portion of the core; and distal ends of the sleeve and theoptical fiber core distal portion form an enlarged light emitting face,the first cladding layer positioned proximally of the second claddinglayer, the second cladding layer extending proximally from the enlargedlight emitting face; and applying the laser light through the enlargedlight emitting face while longitudinally moving the inserted opticalfiber, the application of the laser light causing closure of thevaricose vein.
 2. The method according to claim 1, wherein: the sleevehas: an inner sleeve whose distal end together with the distal end ofthe core form the enlarged light emitting face; and an outer sleevearranged around the inner sleeve; and the step of applying the laserlight includes applying the laser light through the enlarged lightemitting face formed by the distal ends of the inner sleeve and theoptical fiber core.
 3. The method according to claim 1, wherein thesleeve further includes an outwardly bulging portion.
 4. The methodaccording to claim 1, wherein the step of inserting into a varicose veinan optical fiber includes inserting the optical fiber without the aid ofa treatment sheath.
 5. The method according to claim 1, wherein: thesleeve further includes an outwardly bulging portion; and the step ofinserting into a varicose vein an optical fiber includes inserting theoptical fiber without the aid of a treatment sheath.
 6. The methodaccording to claim 1, wherein: the sleeve further includes an outwardlybulging portion; and the step of inserting into a varicose vein anoptical fiber includes inserting the optical fiber without beinginserted through a treatment sheath such that the bulging portion of thesleeve is in contact with blood in the varicose vein during insertion.7. The method according to claim 1, further comprising inserting into avaricose vein a treatment sheath, wherein the optical fiber is insertedinto the varicose vein through the treatment sheath.
 8. The methodaccording to claim 1, prior to the step of inserting into a varicosevein an optical fiber, further comprising: inserting a micropuncturesheath/dilator combination set into a blood vessel over a guidewire;removing the guidewire and the dilator to leave the insertedmicropuncture sheath in place; wherein the step of inserting into avaricose vein an optical fiber includes inserting the optical fiberthrough the micropuncture sheath without the aid of a treatment sheath.9. The method according to claim 1, wherein: a plurality of spacedmarkers are disposed along a wall of the optical fiber; and the step ofapplying the laser light through the light emitting face includes usingthe spaced markers to control the speed of withdrawing the insertedoptical fiber.
 10. The method according to claim 1, wherein: the distalends of the sleeve and the optical fiber core form a heat fused enlargedlight emitting face; and the step of applying the laser light includesapplying the laser light through the heat fused enlarged light emittingface.
 11. The method according to claim 1, wherein: the sleeve isindex-matched to the core; the distal ends of the sleeve and the opticalfiber core form a heat fused enlarged light emitting face; and the stepof applying the laser light includes applying the laser light throughthe heat fused enlarged light emitting face.
 12. The method according toclaim 1, wherein: the sleeve is index-matched to the core and defines anannular air gap serving as the second cladding layer; the distal ends ofthe sleeve and the optical fiber core form a heat fused enlarged lightemitting face; and the step of applying the laser light includesapplying the laser light through the heat fused enlarged light emittingface.
 13. The method according to claim 1, wherein the step of insertingincludes inserting the optical fiber whose emitting face has beenenlarged by 30% to 73% in effective diameter E.
 14. The method accordingto claim 12, wherein the step of inserting includes inserting theoptical fiber whose emitting face has been enlarged by 30% to 73% ineffective diameter E.
 15. The method according to claim 14, wherein thestep of inserting includes inserting the optical fiber whose emittingface has been enlarged by 47% to 67% in effective diameter E.
 16. Themethod according to claim 14, wherein the step of inserting includesinserting the optical fiber whose enlarged emitting face reduces averagepower density by 54% to 61%.
 17. The method according to claim 2,wherein: the step of inserting includes inserting the optical fiberwhose enlarged light emitting face extends distally from the distal endof the outer sleeve.
 18. The method according to claim 15, wherein: thesleeve has: an inner sleeve whose distal end together with the distalend of the core form the enlarged light emitting face; and an outersleeve arranged around the inner sleeve; and the step of insertingincludes inserting the optical fiber whose enlarged light emitting faceis positioned distally from the distal end of the outer sleeve.
 19. Anendovascular treatment method for causing closure of a vein segmentcomprising: inserting into the vein segment an optical fiber having acore through which a laser light travels, wherein: the core has aproximal portion surrounded directly by a first cladding layer and adistal portion in which the first cladding layer that surrounds thedistal portion has been replaced by a second cladding layer differentfrom the first cladding layer, the distal portion disposed distally ofthe proximal portion; and a sleeve is arranged around the distal portionof the core; distal ends of the sleeve and the optical fiber core distalportion form a convex heat fused enlarged light emitting face, the firstcladding layer positioned proximally of the second cladding layer, thesecond cladding layer extending proximally from the enlarged lightemitting face; and after the optical fiber has been inserted into thevein segment, applying the laser light through the convex heat fusedenlarged light emitting face while withdrawing the inserted opticalfiber across the vein segment, in an amount sufficient to cause closureof the vein segment.
 20. The method according to claim 19, wherein: thesleeve has: an inner sleeve whose distal end together with the distalend of the core form the heat fused enlarged light emitting face; and ametallic outer sleeve arranged around the inner sleeve; and the step ofapplying the laser light includes applying the laser light through theheat fused enlarged light emitting face formed by the distal ends of theinner sleeve and the optical fiber core.
 21. The method according toclaim 19, wherein the step of inserting includes inserting the opticalfiber without the aid of a treatment sheath.
 22. The method according toclaim 19, further comprising inserting into the vein segment a treatmentsheath, wherein the optical fiber is inserted into the vein segmentthrough the treatment sheath.
 23. The method according to claim 19,wherein: the sleeve is index-matched to the core.
 24. The methodaccording to claim 19, wherein: the sleeve is index-matched to the coreand defines an annular air gap serving as the second cladding layer; andthe step of applying the laser light includes applying the laser lightthrough the heat fused enlarged light emitting face with the annular airgap acting to contain the laser light within the core.
 25. The methodaccording to claim 19, wherein the step of inserting includes insertingthe optical fiber whose emitting face has been enlarged by 30% to 73% ineffective diameter E.
 26. The method according to claim 24, wherein thestep of inserting includes inserting the optical fiber whose emittingface has been enlarged by 30% to 73% in effective diameter E.
 27. Themethod according to claim 26, wherein the step of inserting includesinserting the optical fiber whose emitting face has been enlarged by 47%to 67% in effective diameter E.
 28. The method according to claim 27,wherein the step of inserting includes inserting the optical fiber whoseenlarged emitting face reduces average power density by 54% to 61%. 29.The method according to claim 19, wherein: the sleeve has: an innersleeve whose distal end together with the distal end of the core formthe enlarged light emitting face; and an outer sleeve arranged aroundthe inner sleeve; and the step of inserting includes inserting theoptical fiber whose enlarged light emitting face extends proximally ordistally from the distal end of the outer sleeve.